Adding a UIView class outside ViewController class to show subview

Question

I have been check many close answers here, no one can solve my stupid problem..

My problem is: I have 2 classes, UIViewController classA and UIView classB.

A button(classA) trigger to process(classB), then show the subview on screen(classA). But it doesn't work.

classA .m:

@implementation ViewController
...

- (IBAction)trigger:(UIButton *)sender {
    [classB  makeViewOn];
}

classB .h:

#import <UIKit/UIKit.h>

@interface classB : UIView
+ (void)makeViewOn;

@end

classB .m:

#import "classB.h"

#import "ViewController.h"

@implementation classB

+ (void)makeViewOn
{        
    ViewController *pointer = [ViewController new];
    UIWindow *window = pointer.view.window;

    classB *overlayView = [[classB alloc] initWithFrame:window.bounds];
    overlayView.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.5f];
    overlayView.userInteractionEnabled = YES;

    [pointer.view addSubview:overlayView];
}

@end

If I do this in only one class, UIViewController, it works fine; However, if I do this on two separate class(UIViewController & UIView), how can I fix it?

Am I doing something wrong on basic concepts of communicating between classes?

Thanks a lot!

Answer 1

Firstly, you are creating a new object named pointer of class ViewController, therefore your classB object overlayView is not being added as a subview to the classA but rather to the object pointer.

Secondly, if you print and check your window.bounds its returning (null).

Modify you class method in classB

+ (void)makeViewOnParentView:(id)sender;

+ (void)makeViewOnParentView:(id)sender
{        
        ViewController *pointer = (ViewController*)sender;
        //UIWindow *window = pointer.view.window;
        CGRect rect=pointer.view.frame;

        classB *overlayView = [[classB alloc] initWithFrame:CGRectMake(0, 0,rect.size.width, rect.size.height)];
        overlayView.backgroundColor = [[UIColor greenColor] colorWithAlphaComponent:0.5f];
        overlayView.userInteractionEnabled = YES;

        [pointer.view addSubview:overlayView];
}

And in your classA call the method

[classB makeViewOnParentView:self];

Hope this will work for you...